In recent years, there have been developments for improving protection performance especially for the heads of occupants when a vehicle side is subjected to an impact force.
Japanese Patent No. 3510061, for example, proposes an occupant protection device configured to store a roof side airbag from a pillar along a roof side edge so that the roof side airbag is inflated in the form of a curtain along side glasses when subjected to an impact force above a certain level. The roof side airbag is often called a side curtain airbag.
This occupant protection device is configured so that the roof side airbag is stored in a pillar space and a roof space; an inflator is mounted to a roof side rail; the roof side airbag is mounted to the roof side rail by bolts at certain pitches; and the roof side airbag is connected to the inflator via a gas supply pipe. With this occupant protection device, when a sensor detects reception of an impact force above a certain level laterally of the vehicle body, the inflator generates gas to inflate the roof side airbag along the side glasses toward the passenger compartment.
Roof side airbags in the related art are configured with a plurality of inflating portions aligned longitudinally. The front one of the inflating portions inflates, breaking a pillar garish.
Gas supplied from the inflator into a rear upper portion of the roof side airbag rapidly flows into all the inflating portions including the front inflating portion. Gas is thus supplied from the rear upper portion of the roof side airbag, so that the gas pressure to inflate the front inflating portion is relatively small. Therefore, when the front inflating portion inflates, breaking the pillar garnish, the load applied to the pillar garnish can be small.
However, some vehicles are of the type provided with three rows of seats, a front seat, a middle seat and a rear seat. For such vehicles also, it is required to adequately protect all occupants seated in three rows of seats with a roof side airbag. Accordingly, it is necessary to elongate the roof side airbag and to increase the flow of gas for inflating the roof side airbag.
Also, in the related-art roof side airbag, gas flows in from the rear upper portion, so that a gas inflow path to the front inflating portion is long. This results in an increase in pressure loss in the gas inflow path, lowering the gas pressure to inflate the front inflating portion.
With this in view, it is conceived to provide two front and rear gas inlets in a longitudinally substantially middle portion to rapidly, uniformly and sufficiently inflate all the inflating portions including the front inflating portion. However, only providing the gas inlets in the substantially middle portion can increase the gas pressure to inflate the front inflating portion. Given this, it is very difficult to provide a suitable gas pressure. Therefore, when inflating and deploying a roof side airbag, it is necessary to uniformly and sufficiently inflate the entire bag so that an excessive load is not applied from the roof side airbag to a pillar garnish at a front pillar.
Further, the provision of the two front and rear gas inlets in the substantially middle portion of the roof side airbag can separate a portion around the gas inlets into front and rear portions. Consequently, when folding the roof side airbag, the front and rear portions can be twisted relative to each other in the vicinity of the middle portion, which needs to be prevented.
Furthermore, in occupant protection devices in the related art, an inflator and a roof side airbag are mounted separately to a roof side rail, causing variation in the positional relationship of the roof side airbag to the inflator. For example, mounting to the roof side rail an assembly unit in which a roof side airbag is connected to an inflator via a gas supply pipe causes the necessity of mounting the inflator and the roof side airbag separately to the roof side rail because the roof side airbag is a member made from cloth and having flexibility, resulting in variation in the positional relationship of the roof side airbag to the inflator. Consequently, the roof side airbag can be fixed in a twisted condition relative to the inflator. This twist phenomenon is not favorable for adequately supplying gas from the inflator to the roof side airbag. Also, the separate mounting of the inflator and the roof side airbag to the roof side rail causes problems that mounting points are increased; the number of components is increased; and mounting man-hours are increased. That is, it is necessary to mount an inflator and a roof side airbag more properly to a vehicle body, and also to reduce the number of mounting components and mounting man-hours.
Further, as described above, it is necessary for a vehicle with three rows of seats to elongate a roof side airbag longitudinally of the vehicle body. For the uniform flow of gas into the entire airbag, it is necessary to divide the airbag into a plurality of bag portions. In order to inflate and deploy the bag portions in stable condition, it is necessary to provide an inner tube in the roof side airbag to distribute gas to the bag portions through the inner tube.
However, gas generated from an inflator can become a pulsating flow. The pulsating flow of gas can cause a distal end portion of the inner tube to flutter and get into a certain bag portion through an opening formed in the bag portion, preventing inflation and deployment of the roof side airbag. Therefore, it is necessary to prevent fluttering of the inner tube when a pulsating flow is produced in the flow of gas.
Furthermore, it is necessary to allow gas from the inner tube to smoothly flow into certain ones of the divided bag portions.
On the vehicle body, a protrusion can be produced by spot welding or the like. To protect a roof side airbag from such a protrusion, the roof side airbag is covered by a protector cloth, and the protector cloth is attached to the roof side airbag with tape. The operation of attaching the protector cloth to the roof side airbag with tape is performed when the roof side airbag is mounted to the roof side of the vehicle body.
The mounting operation of the roof side airbag is performed using a relatively small space. The use of the small space for attaching the protector cloth to the roof side airbag with tape has a disadvantage that the operation takes time.
For mounting a roof side airbag to a roof side rail, mounting brackets are generally used. It is preferable to increase the strength of the mounting brackets so that when an occupant strikes a mounting bracket, the impact is absorbed by deformation of the mounting bracket.
Such mounting brackets are arranged along the roof side rail at predetermined intervals, so that some mounting bracket is located above a pillar. The pillar is provided with a pillar garnish facing the vehicle interior to also serve to absorb impact. When an occupant strikes the mounting bracket located above the pillar, the occupant also strikes the pillar garnish at the same time. Since the occupant strikes the pillar garnish, the pillar garnish absorbs part of the impact. Consequently, an impact applied to the mounting bracket is made relatively small.
On the other hand, when an occupant strikes a mounting bracket located off the pillar, the occupant only strikes the mounting bracket without striking the pillar garnish, resulting in a relatively great impact applied to the mounting bracket.
The difference in impact applied to the mounting brackets causes the problem that if the mounting brackets have the same strength, it is difficult to well absorb respective impacts applied to the mounting brackets.
Further, in order to mount a roof side airbag to a vehicle with three rows of seats, the roof side airbag is relatively elongated as described above. This increases intervals between mounting brackets for mounting the roof side airbag to the vehicle body, making it difficult to fit the roof side airbag along the vehicle body, and leaving room for improvement.
Furthermore, since the relatively elongate roof side airbag is likely to be twisted, when the roof side airbag is mounted to the roof side rail, it is necessary to hold the roof side airbag to prevent twisting. However, it is a difficult operation to mount the elongate roof side airbag to the vehicle body while holding it, resulting in low workability. Thus, the mounting operation of the roof side airbag is time-consuming and leaves room for improvement.